Delayed recovery of movement-related cortical function in Parkinson's disease after striatal dopaminergic grafts

Intrastriatal transplantation of dopaminergic neurones aims to repair the selective loss of nigrostriatal projections and the consequent dysfunction of striatocortical circuitries in Parkinson's disease (PD). Here, we have studied the effects of bilateral human embryonic dopaminergic grafts on the movement-related activation of frontal cortical areas in 4 PD patients using H2 15O positron emission tomography and a joystick movement task. At 6.5 months after transplantation, mean striatal dopamine storage capacity as measured by 18F-dopa positron emission tomography was already significantly elevated in these patients. This was associated with a modest clinical improvement on the Unified Parkinson's Disease Rating Scale, whereas the impaired cortical activation was unchanged. At 18 months after surgery, there was further significant clinical improvement in the absence of any additional increase in striatal 18F-dopa uptake. Rostral supplementary motor and dorsal prefrontal cortical activation during performance of joystick movements had significantly improved, however. Our data suggest that the function of the graft goes beyond that of a simple dopamine delivery system and that functional integration of the grafted neurones within the host brain is necessary to produce substantial clinical recovery in PD.

A synthetic gene coding for the green fluorescent protein (GFP) is a versatile reporter in Chlamydomonas reinhardtii

The use of Chlamydomonas reinhardtii as a model system has been hindered by difficulties encountered in expressing foreign genes. We have synthesised a gene encoding green fluorescent protein (GFP) adapted to the codon usage of C. reinhardtii (cgfp). After verifying the gene was functional in Escherichia coli, the cgfp was fused in frame to the phleomycin resistance gene ble from Streptoalloteichus hindustanus and expressed in C. reinhardtii under control of the rbcS2 promoter and intron sequences. The GFP-fluorescence was seen only in the nucleus demonstrating the nuclear accumulation of the Ble-GFP fusion protein. The cgfp was also fused to the chlamyopsin gene, cop, and expressed in C. reinhardtii under control of the cop promoter. The eyespot became fluorescent indicating that the opsin-GFP fusion protein was correctly directed into the eyespot along with the endogenous unmodified opsin. We conclude that cgfp provides a useful tool to visualize protein synthesis and localisation in vivo in C. reinhardtii and possibly in related green algal species.

Glial cell line-derived neurotrophic factor protects dopaminergic neurons from 6-hydroxydopamine toxicity in vitro

Glial cell line-derived neurotrophic factor (GDNF) is a potent and specific neurotrophic factor for dopaminergic neurons. GDNF has been previously shown to protect dopaminergic neurons from lesion-induced degeneration in vivo. In this study we investigated the effect of GDNF on 6-hydroxydopamine (6-OHDA)-treated dopaminergic neurons in vitro. In dissociated cultures of embryonic rat mesencephalon, 6-OHDA exhibited a dose-dependent cytotoxicity on tyrosine hydroxylase (TH)-immunoreactive neurons. After pre-treatment with GDNF, however, 6-OHDA-induced loss of dopaminergic neurons was effectively reduced. It has been shown recently that GDNF signals through the receptor tyrosine kinase Ret and the GDNF receptor-alpha (GFR-alpha). By RT-PCR, we found both Ret- and GFR-alpha-genes to be expressed in the cultured mesencephalic cells. We propose that the neuroprotective effect of GDNF on 6-OHDA-treated dopaminergic neurons in vitro is most likely mediated by functional Ret receptor signaling pathways.

Electrical stimulation of the posteroventral pallidum influences internally guided saccades in Parkinson's disease

Chronic electrical stimulation of the posteroventral internal pallidum, a recently developed treatment option in advanced Parkinson's disease (PD), improves bradykinesia, rigidity and medication-induced dyskinesia. Apart from disturbances of the somatic motor system, PD is also characterized by disturbances of saccadic eye movements with hypometric and delayed internally guided saccades. We examined these internally guided eye movements (memory-guided and anti-task saccades) in a patient with bilaterally implanted stimulation electrodes, when stimulation was turned on and off. The electrical stimulation not only improved the bradykinesia and rigidity, but also the internally guided saccades by shortening the latency of the anti-saccades and increasing the gain of the memory-guided saccades. This finding supports the idea that the oculomotor pathways through the basal ganglia are organized like the somatic motor pathways and that stimulation of the posteroventral pallidum influences both.

What is the optimal dose of botulinum toxin A in the treatment of cervical dystonia? Results of a double blind, placebo controlled, dose ranging study using Dysport. German Dystonia Study Group

OBJECTIVES

Botulinum toxin injections have become a first line therapeutic approach in cervical dystonia. Nevertheless, published dosing schedules, responder rates, and frequency of adverse events vary widely. The present prospective multicentre placebo controlled double blind dose ranging study was performed in a homogenous group of previously untreated patients with rotational torticollis to obtain objective data on dose-response relations.

METHODS

Seventy five patients were randomly assigned to receive treatment with placebo or total doses of 250, 500, and 1000 Dysport units divided between one splenius capitis (0, 175, 350, 700 units) and the contralateral sternocleidomastoid (0, 75, 150, 300 units) muscle. Assessments were obtained at baseline and weeks 2, 4, and 8 after treatment and comprised a modified Tsui scale, a four point pain scale, a checklist of adverse events, global assessment of improvement, and a global rating taking into account efficacy and adverse events. At week 8 the need for retreatment was assessed and then the code was unblinded. For those still responding, there was an open follow up until retreatment to assess the duration of effect.

RESULTS

Seventy nine per cent reported subjective improvement at one or more follow up visits. Decreases in the modified Tsui score were significant at week 4 for the 500 and 1000 unit groups versus placebo (p<0.05). Additionally positive dose-response relations were found for the degree of subjective improvement, duration of improvement, improvement on clinical global rating, and need for reinjection at eight weeks. A significant dose relation was also established for the number of adverse events overall and for the incidence of neck muscle weakness and voice changes.

CONCLUSION

Magnitude and duration of improvement was greatest after injections of 1000 units Dysport; however, at the cost of significantly more adverse events. Therefore a lower starting dose of 500 units Dysport is recommended in patients with cervical dystonia, with upward titration at subsequent injection sessions if clinically necessary.

[Psychosomatic aspects of idiopathic spasmodic torticollis. Results of a multicenter study]

Idiopathic spasmodic torticollis (IST) is one of the most frequent dystonic movement disorders. Its classification as a focal dystonia, as well as its treatment with botulinum toxin resulted in groups of patients being regularly seen by neurologic specialists. In a multicentre study, we investigated psychosocial changes, coping and psychopathology, and their interrelations with signs, symptoms and course. 256 patients were included in the study (59.3% women, 40.7% men). The mean age was 49.1 years. Rotating torticollis occurred more often than latero-retrocollis and antero-retrocollis. A family history of IST was seen in 3.1% of the total sample. 34% of the patients had additional dystonic symptoms. Most frequently, these affected the upper extremities (13%), less often the legs. 19.1% of the patients had experienced a period of complete remission. The General Symptom Index of the SCL 90-R in 27% of the patients ranged above the double standard deviation of the normal controls, indicating a clinically significant psychopathology.

Spasmodic torticollis - a multicentre study on behavioural aspects II: signs, symptoms and course

This paper deals with signs, symptoms and course in spasmodic torticollis (ST). Two hundred and fifty-six patients were included in the study, 59.3% women, 40.7% men. The mean age was 49.1 years. Rotating torticollis out-numbered latero- and antero-retrocollis. A family history of ST occurred in 3.1% of the total sample. First degree relatives were affected in 2.3%. Thirty-four per cent of the patients had additional dystonic symptoms. Most frequently these affected the upper extremities (13%), and less often the legs. Of the patients 19.1% had experienced a period of complete remission. The correlations between the severity of the signs and the neurological symptoms are surprisingly weak.

Acute MPTP treatment produces no changes in mitochondrial complex activities and indices of oxidative damage in the common marmoset ex vivo one week after exposure to the toxin

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) has been shown to cause a Parkinsonian syndrome in man and non-human primates. Hypotheses concerning the pathogenetic mechanisms of MPTP toxicity on nigro-striatal dopaminergic neurons relate to impairment of mitochondrial function and oxidative stress. However, surprisingly few primate studies addressed these issues ex vivo. Thus, the present study assessed the enzyme activities of the respiratory chain, GSH/GSSG and ubiquinol/ubiquinone content in the MPTP primate model (common marmoset, Callithrix jacchus; 2 mg MPTP-hydrochloride/kg body wt were injected subcutaneously (s.c.) on four consecutive days; animals were sacrificed 7 days after last MPTP exposure). Activities of respiratory chain enzymes were measured in crude homogenates of the caudate nucleus, because the probable toxic metabolite of MPTP, MPP+, is transported into dopaminergic neurons via the dopamine uptake system in striatal synapses and mitochondria are concentrated in axonal terminals. Since MPP+ can damage membranes of axonal terminals of nigro-striatal neurons we measured GSH/GSSG contents in the putamen and ubiquinol/ubiquinone concentrations in the substantia nigra and putamen as indices of oxidative damage. At the time of sacrifice MPTP-induced deficits comprised severe behavioural Parkinsonian symptoms, profound depletion of striatal dopamine and its major metabolites as well as pronounced loss of nigro-striatal neurons. Despite these severe lesions, acute MPTP treatment had no effect on any of the enzymes of the respiratory chain in the caudate nucleus and indices of oxidative damage in both the substantia nigra and putamen. These results suggest that factors other than mitochondrial impairment and/or oxidative stress may be involved in MPTP neurotoxicity in primates. Alternatively, early compensatory mechanisms and/or transient effects could account for the reported results and will be discussed.

Spasmodic torticollis - a multicentre study on behavioural aspects III: psychosocial changes and coping

Psychosocial changes in spasmodic torticollis (ST) affect predominantly social life, professional life and psychological well-being. Concerning social life, 84.6% of the patients felt that they attracted considerable public attention due to their neurological illness and 65% had reduced participation in social events. A substantial number of patients had retired from professional activities; others felt severely impaired in their working capacity. The psychosocial sequelae in ST, however, seemed to depend less on the neurological signs per se than on the physical symptoms and on coping. Depressive coping in particular emerged as a predictor of psychosocial distress.

Neurotoxicity induced by prenatal exposure to MPTP on the monoaminergic and peptidergic systems of the marmoset brain

The neurotoxicity induced by incidental prenatal exposure to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) was studied in three marmosets. The baby marmosets exposed in utero to MPTP looked normal in the first few weeks of life but around 8 to 10 weeks of life they started to behave abnormally and were sacrificed when they were 20 weeks old. A marked reduction in DA levels was found in the baby marmosets prenatally exposed to MPTP as compared to the corresponding age-matched controls and this was highly significant in the caudate nucleus, putamen, and nucleus accumbens. Serotonin content was normal in the caudate and putamen and was only significantly reduced in the nucleus accumbens, hypothalamus, and cingulate cortex. Met-enkephalin levels were reduced in the caudate nucleus, putamen, and globus pallidus. Substance P content tended to be lower in all regions examined; however, the decrease was only statistically significant in the substantia nigra. These results indicate that prenatal exposure to MPTP induces a marked and long-lasting alteration in monoaminergic and peptidergic systems of the primate brain. This observation may provide a new insight into the role of toxins in the etiology of Parkinson's disease.

Psychosocial aspects of Parkinson's disease

Although Parkinson's disease has a definite neurologic basis, patients and relatives experience a multitude of stresses, only partly related to motor symptoms. Subjective and behavioral problems may be regarded as secondary disease symptoms. In an integrated approach, patients and relatives receive psychological counseling and learn new coping strategies for everyday situations. Results show that even elderly patients can make use of structured psychological interventions and change dysfunctional behaviors and cognitions. Measures specifically adjusted to Parkinson's disease are aimed at helping patients make better use of the beneficial effects of medication and counteract the possible negative effects of social and emotional stressors. Relatives need information about the disease and training to cope adequately with difficult caring situations. Future evaluation of medical treatment of Parkinson's disease should consider the interaction of psychological factors and symptom intensity. This interaction may result in momentary changes in the effects of medication because of psychological conditions. In the early stages of the disease, medication has the most positive effect, and psychological interventions should also have the most benefit.

Neurotoxic effect of prenatal exposure to MPTP on the dopaminergic systems of the marmoset brain

MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) was incidentally administered to pregnant marmosets during the whole gestational period, except for the last 15 days before term. The infant monkeys were killed 5 months after birth, and dopamine and its metabolites were measured in the striatum and the nucleus accumbens. Prenatal exposure to MPTP produced a marked dopamine depletion in these brain regions of the offspring, showing that MPTP is able to cross the placental barrier in primates.

The competitive NMDA antagonist CGP40.116 enhances L-DOPA response in MPTP-treated marmosets

Experiments in MPTP-treated non-human primates testing potential antiparkinsonian action have shown both, beneficial and adverse effects of gutamate receptor antagonists. To investigate this matter further, the novel competitive NMDA antagonist CGP40.116 was administered systemically to three adult MPTP-treated marmosets. When coadministered subcutaneously with a subthreshold dose of L-DOPA, 2 mg/kg, CGP40.116 25-250 micrograms/kg, increased locomotor activity. However, when administered alone, CGP40.116 had no effect on locomotor activity.

[The dependence of rapid voluntary contractions on the tremor phase in parkinsonism]

Parkinsonian patients sometimes have problems to produce really fast motor responses. Often, these are significantly delayed in comparison to those of normal controls. In patients with tremor-at-rest, this delay might be induced by some attraction of the movement execution to the tremor oscillator, according to a hypothesis of Hallet et al. (1977). This study now examined the phase relationship between the on-going tremor and the onset of fast voluntary contractions in Parkinson's disease (PD), quantitatively. Five patients with prominent tremor-at-rest performed rapid isometric index finger abductions under self paced (SP) and reaction time (RT) conditions, and force and surface EMG signals from the FDI muscle were analyzed. In both conditions the SP and the RT, data showed that the onset of the contraction mostly occurs during the descending phase of the tremor oscillation and, accordingly, the phasic EMG burst synchronously with the tremor bursts confirming the above mentioned hypothesis.

Morphological and electrophysiological studies of human hippocampal transplants in the anterior eye chamber of athymic nude rats

Human fetal hippocampal tissue from normal women was obtained following elective abortion in the 8th to the 11th week of gestation. The hippocampal tissue was transplanted to the anterior chamber of the eye of adult athymic nude rats, where it was allowed to develop for up to 9 months before histological and electrophysiological evaluation. The transplants were revascularized from the host iris and many grew extensively in oculo. Large neurons were present in all transplants. Immunohistochemical studies revealed glutamic acid decarboxylase-containing terminals and clusters of gamma-aminobutyric acid-positive nerve cell bodies within the transplants, as well as scattered tyrosine hydroxylase-positive and acetylcholinesterase-containing fibers. Single neurons recorded extracellularly from transplants 4-9 months in oculo showed a slow spontaneous discharge, with both complex and single action potentials. Stimulation of the transplant surface evoked a small initial wave followed by a larger and longer-lasting field potential, similar to that seen in hippocampus in situ. A conditioning-testing paradigm was used to evaluate the presence of inhibitory circuitry in the hippocampal transplants. Significant suppression of the evoked test response was seen with interstimulus intervals ranging from 20 to 500 ms. Superfusion of enkephalin (100-300 nM) or penicillin (1600 U/ml) increased slow-wave activity, as did tetanic electrical stimulation. These treatments appeared to generate ictal-like activity, which in some cases persisted as interictal spikes. Illumination of the retina also increased neuronal activity, presumably by reflex activation of cholinergic afferents from the parasympathetic innervation of the iris. Taken together, our data suggest that fragments of hippocampus from aborted first trimester human fetuses, grafted to the eye chamber of rodent hosts, develop many organotypic histological and physiological features. This preparation may provide a unique means for the study of neurobiological properties of human brain in both normal and disease states.

Glutamic acid decarboxylase- and gamma-aminobutyric acid-like immunoreactivities in corticotropin-releasing factor-containing parvocellular neurons of the hypothalamic paraventricular nucleus

The indirect immunofluorescence technique was used to study the relation between corticotropin-releasing factor (CRF) and GABAergic neurons in the rat hypothalamic paraventricular nucleus (PVN). In colchicine-pretreated animals, glutamic acid decarboxylase (GAD)- and GABA-immunoreactive (IR) neurons were observed within the medial part of the parvocellular division of the PVN as well as surrounding the nucleus itself. In general, the GAD antiserum, as compared to the GABA antiserum, revealed stronger IR cells and a higher number of cells in the PVN. CRF-IR cells were observed throughout the whole rostrocaudal extension of the PVN, but predominantly in its dorsal medial parvocellular part. Adjacent sections stained, respectively, with antisera against CRF, GAD or GABA, revealed overlapping distributional patterns within the parvocellular part of the PVN. Employing a direct double-staining technique with sheep GAD and rabbit CRF antisera, it was demonstrated that both GAD and CRF immunoreactivities occurred in the same neurons, particularly in the dorsomedial aspect of the parvocellular PVN. GAD-positive neurons located in the ventromedial parvocellular PVN, periventricular nucleus and surrounding the PVN lacked CRF immunoreactivity. In addition, with an elution-restaining technique it was possible to demonstrate that also GABA immunoreactivity was present in some CRF neurons in the dorsomedial parvocellular PVN. Intravenous injection of the retrograde tracer Fast Blue resulted in labelling of neurons in the periventricular area and in both the parvocellular and magnocellular division of the PVN. After processing the sections for GAD/CRF immunohistochemistry, it was possible to demonstrate the presence of retrogradely labelled GAD/CRF cells, pointing at a PVN median eminence projection for these neurons. The present findings demonstrate that a subpopulation of the CRF-containing neurons in the parvocellular division of the PVN in addition are GABAergic, thereby indicating a possible corelease of these compounds, presumably in the median eminence. Possible interactions of GABA within the hypothalamo-pituitary-adrenal axis are discussed.

Plasticity and rigidity in the representation of the human visual field

Neuronal plasticity in the mammalian visual system has been studied with a variety of experimental methods like induction of artificial squint and eye rotation. To investigate neuronal plasticity in the human visual system, we examined a patient with a congenital convergent squint of his left eye, who later suffered a vascular lesion in his left occipital lobe that led to an incomplete hemianopia in his right visual field. The examination revealed that the visual field representation in the striate cortex is rigidly prewired with reference to the anatomical fovea. In contrast, plasticity in the oculomotor system enables the patient to use a functional visual axis that does not correspond to the anatomical fovea. Local alterations of sensitivity within the visual field that indicate interactions among non-corresponding retinal points provide additional evidence of functional plasticity.